Look at your autostart job entries and the associated job descriptions. Ensure that you understand the function of any program that runs automatically when a subsystem starts.
An autostart job entry contains the name of a job description. The job description may contain request data (RQSDTA) that causes a program or a command to run. For example, the RQSDTA might be CALL LIB1/PROGRAM1. Whenever the subsystem starts, the system will run the program PROGRAM1 in library LIB1.